I've encountered this restriction in many cathedrals (our local one does) and they all say the same thing that the rubber feet on tripods on monpods damage the floor. 

Bannning the use of flash I understand - that does upset the worshippers - but the tripod excuse is just silly. Moreos when you consider most cathedrals where built in the middle ages and often used as markets where cattle and sheep wandered around. 

Art gallerys will often refuse as well. They cite copyright reasons and flash damaging paintings. 
Again the flash issue is true there. But the real reason is money, if you take a few photos you're less likely to buy some postcards, guide books or  over priced art prints.    

One solution is a gorrila grip (just don't get caught using it - these things can chip and strip paintwork) or the Blue Peter option -  a bean bag and a very short girlfriend :)

Pinky - you left the lens cap of your mind on again.